Running electrical wire through PVC pipe

[clare]

PolyTwine is best. Doesn't deteriorate and is easy to find

[The Daring Dufas]

There are small rolls at the big box stores in the electrical wiring section.

TDD

[N8N]

Not in my neck o' the woods. Of course, the help in the big boxen wouldn't know a pull string if it fell on their heads. I really do get sick of knowing more about what they sell than the "associates" do.

Of course, the pricing is better at the supply house, so I just wait until Saturday AM and go there. Only downside is when, as happened recently, I got snowed in for two Saturdays in a row and thus my home projects ground to a halt...

nate

[Vinny From NYC]

On Thu, 25 Feb 2010 14:00:16 -0800 (PST), N8N wrote Re Re: Running electrical wire through PVC pipe:

"boxen"? Wow, that's soooo cool.

[Oren]

The local HD store here keeps a box of nylon twine at the overhead door exit. Used to bundle several pieces of trim or base molding together.

I've cut 30 - 50 feet before - free. It is there for the customer use.

[Oren]

I know enough that fishing line is not used for pulling wire :-/

A local Casino paid (7.5M?) to have overhead lines and poles removed, so they could expand building. That underground cable was 5 inches wide (130,000 Volts?), along the Vegas Strip. What a pull that was, eh?

[Steve Barker]

[Andrew]

PVC is commonly used for electric wire. Not a problem there. But you should run two separate conduits: one for data signals and one for

120/240V signals. The 120/240V lines are likely to cause interference in the data signals.

[14inches&hard]

The problem is that the hot and ground wires will short together inside the pvc. You will need to install a separate pipe for each wire, unless you wrap each wire with electrical tape so they can not short together. If you use steel wire, be sure it's galvanized or it will rust, or get some stainless steel piano wire, which will last longer. One other thing. Do not run water thru the pipe, or not sewer water either. Even if you tape the wires well, the water or sewerage will cause wires to short out.

[trader4]

Now here's a question. When they build houses why don't they put in a couple empty PVC conduits that run from basement to attic? It sure would make it a hell of a lot easier to run any cables later on. Especially in an age where people are adding all kinds of things, data, voice, AC, etc. Yet, I've never seen this done. I guess there could be some claim that it might let a fire spread easier, but I tend to doubt that's really much of an issue. Even if it were, there would be ways to still do it and seal it off.

[mm]

Isn't that polypropylene, the cheap stuff, often hard to knot? Nylon twine is much nicer and much more expensive.

[krw]

Because it costs money. However, I did this in a few places in my mother's house as they were building it, forty years ago.

It's just a cost that few would every use. A builder isn't going to throw a couple of hundred dollars down the rat hole if he doesn't think people will pay even more. I'm quite sure that you could put it in the contract, though. About now, I'm sure you could get them to agree to let you do it at night. ;-)

[DerbyDad03]

re: "I've cut 30 - 50 feet before - free. It is there for the customer use."

Yes, it's there for customer use, but it's not "free".

It's cost is included in the store's overall operating costs and figured into the prices of the items on the shelf.

The string's not free, the coffee's not free, the non-help you get from many of the associates is not free. You're just not paying for it directly.

OK...I'll grant you the exception where you use the string and drink the coffee without *ever* buying anything from the store. In that case, it would be free.

[Bob F]

14 inches and a 14 IQ.

[bud--]

The NEC explicitly allows Romex to be installed in PVC conduit (352.22). (There are similar permissions for other raceways.)

Heat is a potential problem for multiple cables. It is covered in Wayne's post.

[HerHusband]

Hi David,

I just saw this posting, so I apologize if this has already been answered.

The general code restriction is not to run "romex" style cables in conduit. As you discovered, it is related to heat build-up from the cables in the confined space of the conduit.

I researched this myself a couple years ago, and code does allow exceptions to this when "short" conduit runs are used for physical protection only. For example, I ran romex in conduit at my in-laws house, from surface mounted outlets in the basement, up the wall to the floor structure. It's open at the top for heat to escape, has an anti-short bushing to prevent the conduit edge from cutting into the cable, and is strictly for physical protection. My inspector had no problems with it. But a two story run inside walls would probably be well outside that exception.

Technology changes quickly and it's not economical to install everything in hopes you might someday use it (or worse yet, guess wrong and spend a lot of money on something that's outdated in a few years).

I installed numerous boxes throughout our house with short conduit runs to the crawlspace (capping the ends to prevent drafts and keep out insects). I've replaced and reorganized various cables over the last five years and it's one of the best decisions I've ever made. My only regret is not installing larger conduit, as my needs have far outpaced what I ever thought I would need them for.

Heat concerns are not an issue for data cables (Cat5, Cat 6), Coax, phone, etc., so running conduit now for those is a great idea. Minimal cost and no harm done if you never use it. But you'll be very thankful if you do need it.

I do recommend installing the largest conduit you can afford that will fit in the wall (remember couplings are larger than the outside of the pipe itself). It's unlikely you would ever wish the conduit was smaller, but as you install more "stuff" in coming years, you'll appreciate the extra capacity.

As for power lines, I would run another conduit line (again, as big as will fit), with large junction boxes at each floor. You could run romex cables through the walls/ceilings, then transition to individual THHN wires in the conduit. Individual wires are made for running in conduit, and you can fit more in the same space than romex cables anyway.

Anthony

[hibb]

Hi Anthony,

Thanks for your response. I am not familiar with the term "Romex" cables. The electric wire I run labeled as 12-2 NM-B With Ground. I do not know if it is romex cable or not but it does not mention romex anywhere on the packaging as far as I can see. But I will google romex and see what I can find.

I have already purchased electrical conduit to run a 1 1/2 diameter line from the basement for electrical and another 1 inch conduit for data stuff.

I am going to have speakers at the other end of the room from the computer and mixer so I think I will run conduit up the wall and over the ceiling for those wires in case I want to change those someday. And I will install two Cat5 data outlets. One on each end of the room. I think I will run conduit for those lines too because data wire requirements change so much.

Thanks, David

[HerHusband]

Bud,

Good catch. I missed that in my research a couple of years ago.

Still, the idea of installing conduit now for future work later, would seem to increase the chance that someone might try to fit more than one cable in the conduit.

One option that might prevent that is to install several smaller conduits, such that it would be difficult to fit more than one cable in each. If there were other routes available, it would reduce the temptation to force them in. Just a thought...

Anthony

[gfretwell]

Romex is a brand name for one manufacturer's NM, which is what you have.

[HerHusband]

"Romex" is a brand name. The 12-2 NM-B specification is more important than the brand name. (12-2 will support up to 20 amps for typical runs).

I used the term Romex as that's how most folks refer to it, even though it may be made by other manufacturers. Just like tissues are often called "Kleenex", even though many other companies make them.

That sounds OK to me. Based on the correction "Bud" supplied, you could run a single NM-B cable in the large conduit now. If you ever need to run additional lines, you could pull that cable, install junction boxes top and bottom, and run individual wires in the conduit. Or, go ahead and transition now to save future work.

Better yet, dedicate the 1-1/2 inch line to data needs, and install additional 3/4" conduit runs for future power runs. I would cap any unused lines to keep out insects and drafts.

Oh, and just for clarification, make sure you use grey colored PVC "conduit" and not white PVC water pipe. You wouldn't want someone cutting into what they think is a water line, only to cut into power or data cables.

I mounted in-wall speakers in our living room, but did not use conduit for those lines. It's unlikely I would ever need to relocate the speakers, and if I did it would involve drywall work anyway. But, if you plan to move things around often, or future access would be difficult, the conduit will really make things easier.

Note: If you run speaker cables in the wall, make sure you use speaker cables listed for that purpose. I think it's "CL-2" cable with a fire retardant outer jacket that also makes it easier to pull.

I installed a double-gang sized box on each wall of our living room and every bedroom, with two 3/4" conduits running to our crawlspace. These are for data purposes only. It's not always easy to forsee how furniture might be moved around, and it's not a big cost to add a few more boxes to simplify changes later.

A few of the boxes have gone unused, but I've been surprised how much I've needed most of them. I've run cat5 cables through most of them to connect the computers in various rooms. Two other cat5 cables run to our living room for my blu-ray player and a network media streamer (lets me watch TV shows recorded on the PC in my office).

Install blank cover plates on the boxes you don't use. Special plates with "keystone" jacks let you run all sorts of connections. For instance, the box in my office has two cable lines (one from cable TV, one from an outdoor antenna), two phone lines, and two cat5 ethernet lines.

There isn't anyplace in the house I regret installing the boxes, but I do wish I had installed additional boxes in the home-office, our bedroom, and even the kitchen. I quickly ran out of ports for my home network, so I worked around that by installing a network switch in the crawlspace (I was fortunate to have a power outlet available there). I didn't forsee the need to run much data to the bedroom, so I didn't plan ahead well enough there. I've already had to fish a couple of extra cables in the last five years. A box and conduit would have made things much easier.

Of course, about a month after I ran network cables to every room, I bought a wireless router and don't need the wired connections for my laptop now. :) But the wired connections are still used between desktop PC's and the media devices in our living room. Nice thing about the conduit, I can easily pull out the unused network cables and feed something else in if my needs change later.

Anthony